In a process for manufacturing a semiconductor device or a liquid crystal display device, a substrate processing apparatus of a single substrate processing type, in which substrates are processed one by one, for example, includes a spin chuck that rotates a substrate while holding the substrate approximately horizontally and a nozzle that discharges a processing liquid toward a central portion of a front surface of the substrate rotated by the spin chuck.
In substrate processing that uses the thus arranged substrate processing apparatus, for example, chemical liquid treatment in which a chemical liquid is supplied to the front surface of the substrate that is rotating is performed. The chemical liquid supplied to the front surface of the substrate receives a centrifugal force generated by the rotation of the substrate, and flows on the front surface of the substrate toward its peripheral edge, and spreads in the whole area of the front surface of the substrate. As a result, processing by the chemical liquid is applied to the whole area of the front surface of the substrate.
After completing the chemical liquid treatment, rinsing in which the chemical liquid adhering to the front surface of the substrate is rinsed away by pure water is performed. In the rinsing, for example, a rinse liquid is supplied to the front surface of the substrate being in a rotational state. The rinse liquid supplied to the front surface of the substrate receives a centrifugal force generated by the rotation of the substrate, and flows on the front surface of the substrate toward its peripheral edge, and spreads in the whole area of the front surface of the substrate. As a result, in the whole area of the front surface of the substrate, the chemical liquid adhering to the front surface of the substrate is rinsed away.
After completing the rinsing, an isopropyl alcohol (IPA) liquid is supplied to the front surface of the substrate. The IPA liquid is supplied in a state in which the rotation speed of the substrate is zero or low, and only a zero or small centrifugal force acts on the IPA liquid, and therefore a state in which the liquid stagnates on the front surface of the substrate because of surface tension so as to form a liquid film (this state is hereinafter referred to as “puddled”) is maintained. After the rinse liquid on the front surface of the substrate is replaced with the IPA liquid, the rotation of the substrate is accelerated, and, as a result, the liquid film of the IPA liquid is spun off from the front surface of the substrate, and the substrate is dried.
In the series of processing steps mentioned above, for example, in Patent Document 1, a method (puddle rinse) has been proposed in which, after rinsing is performed, a liquid film of a rinse liquid is held on the front surface of the substrate in a puddled state prior to holding a liquid film of an IPA liquid.